How to build a stable LEGO Bridge

Are you ready for our 6th LEGO® activity for the summer? We made several bridges and then devised a way to test how stable they were.

First, we discussed how to test each bridge. We tried adding weights to the top, but they just fell off rather than breaking the bridge. We tried hanging weights from the bridge, but again they fell off. So we decided to roll a ball towards the bridge to see if it fell over.

You'll need

LEGO® bricks - we used DUPLO

Different size balls

LEGO base

Things to consider

The greater the force behind the ball as you push, the greater the force applied to the bridge. So if you roll a ball hard, the bridge is more likely to fall over than if you roll gently.

To reduce the variable effect of this, the same person rolled the same ball from the same distance each time, trying to keep the force behind the ball the same.

The first bridge fell over straight away, so we strengthened the base, but it still fell over.

We strengthened the bridge further with an extra piece of LEGO® in the middle, and it stayed upright.

At this point, children can think about which features of the bridge made it more or less stable.

Extension Tasks

Test a tower for stability using a pendulum.

Can you build a structure using marshmallows and spaghetti? This activity gets a bit messy and sticky but is brilliant fun!

Make a sweetie house and test for the best 'cement'.

Find out why domes are strong using eggshells. A brittle eggshell may be stronger than you think!

Make a colourful Twirligig like Teach Beside Me!

Or, try one of my many other engineering project ideas for kids!

Last Updated on April 28, 2023 by Emma Vanstone